How The Eye Works

In the nearsighted eye (myopia), images focus IN FRONT of the retina. Nearsightedness causes near objects to be seen more clearly and far objects to appear blurry. Myopia occurs when the curvature of the cornea is too steep, or the eyeball is too long.

In the farsighted eye (hyperopia), images focus BEHIND the retina. Farsightedness causes far objects to be seen more clearly and near objects to appear blurred. Hyperopia occurs when the curvature of the cornea is too flat, or the eyeball is too short.

Astigmatism occurs when the cornea is irregularly shaped. Astigmatism can occur in conjunction with nearsightedness or farsightedness. Here, images focus on more than one point in front of or behind the retina. The result is that all images, whether near or far, may be blurred.

What does 20/20 mean?

Visual Acuity: There’s more to good vision than “20/20.”

If you’re reading this, you’re probably familiar with the vision chart that hangs in every optometrist’s examining room—the one with a big “E” at the top. It’s officially known as a Snellen chart, and it’s been the basis for measuring what’s known as visual acuity since the late 1800s. Think of visual acuity as a quantitative measure of your vision, establishing where your vision is placed on a numeric scale. There are also qualitative measures of your vision, such as your ability to perceive subtle contrast changes, especially in low-light situations. Taken together, these quantitative and qualitative measures determine the overall performance of your vision.

Visual acuity: your vision, by the numbers.

If your visual acuity is determined to be 20/20, you see at 20 feet what a person with normal vision sees at 20 feet. If you have 20/40 vision, you see at 20 feet what a person with 20/20 vision would see at 40 feet. And, if you’re one of the lucky ones (e.g., 20/15), you can see at 20 feet what others would have to move closer (15 feet) to see. Your visual acuity is an important measure of your vision. Many common problems can be identified by this measurement method, including the ones you’ve most likely heard of before—like nearsightedness and farsightedness.

Beyond the numbers: your vision’s quality

There are also qualitative factors affecting your vision. A number of considerations such as contrast sensitivity also contribute to your vision’s performance. Contrast sensitivity is a measure of the ability to discern subtle changes in a visual image. Many routine visual tasks—recognizing a face, for example—rely more upon contrast sensitivity than visual acuity. Problems believed to be associated with poor visual quality are normally most apparent in low-light situations.

Understanding your vision requires taking both the quantitative and qualitative measures into consideration. This is because it’s possible to possess very good visual acuity yet have poor visual quality, and vice versa. It’s important to consider both as you make your decision about laser vision correction in Silicon Valley, San Francisco Bay, San Jose, Walnut Creek, and Santa Rosa.

Low-light vision problems

In addition to those vision problems you’ve probably heard of before—the lower-order aberrations like nearsightedness and farsightedness—there are common vision problems known as higher-order aberrations that can also affect your vision. Higher-order aberrations are widely believed by ophthalmic experts to contribute to common night vision problems, including glare and halos.

Higher-order aberrations cannot be corrected through traditional LASIK procedures. Similarly, glasses and contact lenses are unable to help with these vision problems. An exciting new procedure, called Wavefront LASIK, is capable of correcting both lower-order and higher-order aberrations.

Diagnosing higher-order aberrations

Higher-order aberrations are diagnosed and measured using Wavefront maps. These maps are plotted by passing a narrow ray of eye-safe light through the optical system and measuring the optical distortions as the light exits the eye. These patterns are then compared with the flat Wavefront associated with normal vision. An ideal Wavefront map would be perfectly flat.

Our commitment to you

You rely on your eyes. You trust them to help you make sense of the world. To warn you of danger. To reveal beauty. And to show you the faces of loved ones.

When it comes to your precious eyes, you can count on LaserVue Eye Center. LaserVue is committed to providing technologically advanced, high-quality vision care in its state-of-the-art laser eye surgery centers in the San Francisco Bay Area, San Jose, Walnut Creek, and Santa Rosa.

Since 1996, thousands of Bay Area residents, including countless doctors, have entrusted LaserVue with their eye care. The expertise, clinical excellence, and specialized focus of our fellowship-trained surgeons have made them recognized San Francisco Bay Area, Walnut Creek, Santa Rosa and Santa Rosa cataracts and LASIK surgery specialists.

Not only can you rely on their outstanding medical qualifications, you can also trust that your LaserVue doctor will be there for you throughout all phases of your care—from the exam to surgery, and through the phases of follow-up. That continuity of care ensures you the best outcomes possible.

You can also rely on LaserVue’s advanced Custom Wavefront LASIK technology. From the beginning, LaserVue has been on the forefront of technology. We are committed to using the most advanced, precise, and reliable LASIK equipment available in the San Francisco Bay Area, San Jose, Walnut Creek, and Santa Rosa.

We are proud to have been the first center in the United States to offer the VISX™ STAR S4 laser, uniquely featuring three-dimensional eye tracking and auto-centering, making the LASIK procedure safer and more precise. Because our number one focus is on quality and safety, we continue to reinvest in the technology as it evolves.